1. Technical Field
The present invention relates in general to clustered data processing systems and in particular to management and utilization of shared storage within a clustered data processing system. Still more particularly, the present invention relates to an improved method and system for node failure recovery based on utilization of shared, distributed storage within a clustered data processing system.
2. Description of the Related Art
Virtualized data processing system configuration, which provides the virtualization of processor, memory and Operating System (OS) resources are becoming more and more common in the computer (and particularly the computer server) industry. To a lesser extent, storage virtualization is also known and provided in limited environments. However, within the virtualization computing environment, storage virtualization and management is implemented as a separate virtualization model from server virtualization and management. Thus, different client logical partitions (LPARs) associated with different virtualized server systems may access the same storage access network (SAN) storage. However, the client LPARs on one server do not have any “knowledge” of whether the storage access network (SAN) disk that the client LPAR is trying to access is being used by some other client LPAR belonging to another server. The conventional implementation of distributed server systems providing storage virtualization within shared SAN storage can cause data integrity issues and may potentially cause data corruption and client partition crashes.
Live partition mobility (LPM) is the practice of moving a virtualized client partition from one server to another without appearing to interrupt operations on the client. However, failures occasionally occur during these LPM events. Unfortunately, conventional approaches have not been effective in handling hardware failures during LPM operations. This is a very complex problem because the state permutations are considerable, and there is no single node that can be relied upon to survive the failure. The traditional approach does not work in the clustered environment because in addition to cleaning up storage resources that were orphaned by the failure, there is not synchronization of relational information for the various nodes. With current approaches, recovery from the failure(s) would require a slow node by node accounting and cleanup process which would limit the function of the cluster (potentially a loss of service for the client partition) for some amount of time.